The present invention relates to operativity of a portable digital camcorder.
The prior art relevant to the portable digital camcorder has been published as an electronic photograph system, that is, the so-called electronic still camera that is arranged to record a still image signal as a video signal in a memory composed of a semiconductor (termed as a semiconductor memory or simply a memory) as disclosed in JP-A-2-292974. With recent prevail of personal computers, recording mediums such as semiconductor memories and harddisks are progressively made lower in cost, smaller in size, and greater in capacity. At a time, the advance of signal compressing technology such as JPEG or MPEG allows even the small-sized equipment to record greater number of still images and moving ones. Taking a harddisk drive as an example, the resulting harddisk drive is kept as small as a card and has as great a capacity as about 300 Mbytes.
This type of harddisk drive enables to record about 3000 still images through the use of the JPEG compression and about 20-minutes moving picture through the use of the MPEG compression. It is thus necessary to improve the operativity of the portable equipment for retrieving, grouping, and deleting a great deal of recording data. The technique disclosed in JP-A-2-292974, however, does not provide means for retrieving a great deal of recording data quickly and easily. In actual, therefore, the technique does not have any means except the method of retrieving the great deal of recorded data as checking all images reproduced on screen from the recorded data.
In case that 3000 JPEG still images are recorded on a feasible media such as the aforementioned harddisk drive and then are retrieved as expanding those images on the screen one by one, about one second for expanding one JPEG still image is required. It means that the expansion of 3000 images needs about one hour. This method lacks in practicability. In order to retrieve a great deal of data, therefore, it is necessary to enhance the operating speed of the system.